A device for gas sampling with a detector tube is known from DE 733 715 B. A double-acting reciprocating pump, in which two pumps with hollow piston rods are arranged opposite each other, is provided for taking gas samples. A hollow housing with an insertion pipe is located between the free ends of the piston rods for receiving the detector tube. The interior space of the housing is provided with a filter mat, with which toxic substances, which have not been fully absorbed by the detector tube, are to be absorbed. Harmful gas shall be prevented with the filter mat from entering the pumps. Details of the properties of the filter mass cannot be found in DE 733 715 B.